Based on your question, it sounds to me like you are looking for a couple of different pieces of functionality.

First, you want to take your current implementation of a web-based email program, scrap it, and replace it with something new.

At its most basic level, this is something that is rather easily handled by the Mail::Sendmail package. A simple front-end UI is easy enough to toss together for it, and the docs for the package cover its basic functionality quite well.

Secondly, you're looking for something with white/blacklists, as well as spam monitoring. For this, you could do much worse than Mail::SpamAssassin. I use this package on my personal Linux systems to catch and classify my spam. One of the features I like best about it is the fact that it includes a Bayesianspam filter (note: both of the above links are good reads for those interested in the theory behind Bayesian spam filtering.)

At its most basic level, this is something that is rather easily handled by the Mail::Sendmail package. A simple front-end UI is easy enough to toss together for it, and the docs for the package cover its basic functionality quite well.

Ummm - no. A webmail (even a basic webmail) is much more than that. Not only does it need to send the mail (something Mail::Sendmail does well) it needs to be able to unpack MIME, make attachements available for download, display what can be displayed, allow the user to delete, forward and refile mail between folders, maintain addressbooks, etc, etc, etc.

Secondly, you're looking for something with white/blacklists, as well as spam monitoring.
You misunderstand. We have spam assassin running on several servers (coordinated with clamd), we just need a way to let the users SET the black/white lists that are used by that setup.

Please understand: what we already have is a fairly sophisticated setup, it's just that the PHBs want something prettier/more powerfull and cheaper (i.e. they don't want to pay someone to add a bit to what we already have - they are convinced there must be something "almost right" already out there).

If I can find a prettier Perl solution, great. Otherwise, I may be stuck with hacking what we need into IMP/horde :-(.

Went to join the gridlock to see it
Held an eclipse party
Watched a live feed
I cn"t see tge kwubosd to amswr thus
I tried to see it, but 8000 miles of rock got in the way
What eclipse?
Wanted to see it, but they wouldn't reschedule it
Read the book instead